This invention relates to an apparatus and method for forming dynamoelectric machine field windings, and more particularly to an apparatus and method for directly forming such windings in the slots defined by the blades of coil transfer or insertion apparatus. More specifically, the invention pertains to an apparatus and method for forming such windings with selected numbers of interconnected groups of concentrically disposed coils having selectively variable configurations depending upon the number of poles and the length of the stator core of the dynamoelectric machine to be wound.
Conventional methods for placing dynamoelectric machine field windings in the slots of a stator core are of two general types: the first involving the winding of coils directly into the slots of the core; the second involving the prewinding of coils, the transfer of the prewound coils onto the blades of coil insertion apparatus, and the insertion therefrom into the slots of the core. In the Arick et al U.S. Pat. No. 3,903,933 dated Sept. 9, 1975 and in the Vogel et al U.S. application Ser. No. 590,158 filed June 25, 1975, now U.S. Pat. No. 3,985,163, the disclosures of which are incorporated herein by reference, there are disclosed methods for directly winding coils in the slots defined by the blades of coil transfer apparatus by pushing magnet wire through guide means movable in a predetermined path relative to the blades of the coil transfer apparatus. The apparatus and methods disclosed by the aforesaid U.S. patent and application afford distinct advantages over conventional apparatus and methods for placing windings in the slots of a stator core. In particular, such apparatus and methods do not involve the winding or wrapping of the magnet wire under tension around an element but instead employ a gentle pushing process of placing the magnet wire onto the blades of coil transfer apparatus which subjects the wire to far less abuse than the prior apparatus which wound wire under tension. Since the thickness and composition of the insulation coating on magnet wire is dictated in part by the tension and abrasion to which the wire is subjected, a winding forming apparatus and method which does not involve the winding of wire under tension around an element permits the use of less costly magnet wire having insulating coatings of the required electrical properties but of less thickness or abrasion resistance.
Although the apparatus of the aforesaid U.S. Pat. No. 3,903,933 and U.S. application Ser. No. 590,158 are well suited for forming certain types of windings for dynamoelectric machines, there is a need for an apparatus and method of similar character which may be automatically controlled for forming complete sets of windings with various numbers of interconnected groups of concentrically disposed coils having various configurations without requiring any major change in the winding apparatus configuration or setup. The induction motors which probably comprise the majority of dynamoelectric machines manufactured at this time utilize a stator core having a number of angularly spaced apart slots within which coils of wire are arranged to form two or more pole winding groups. Each pole winding group generally comprises a plurality of coils of different sizes concentrically arranged with respect to the same radial polar center on the stator core. Different sizes or configurations of the coils are required for motors of different sizes as well as for motors having different numbers of poles.